Diocletian’s Palace in Split stands as one of the best-preserved examples of late Roman architecture. Constructed during a period of widespread instability (295 – 305 AD), it represents a new type of fortified and luxurious imperial residence, conceived by Emperor Diocletian and his skilled architects. The northern half of the monumental complex was designed to accommodate the military and support staff, while the southern half was reserved for the emperor’s living quarters and religious functions.
Centuries of building activities have erased the original layout of the imperial residence on the upper floor, but the substructures, commonly known as the substructures, in the southern part of Diocletian’s Palace retain the original form and arrangement of the emperor’s private apartments. Their construction was dictated by the geological foundation, made up of sea cliffs that descend steeply from north to south. The substructures (ground-floor halls) served not only to level the southern part of the site with the higher northern terrain, but also acted as structural supports, allowing the imperial apartments to be built at an elevated level while protecting them from sea and underground moisture. From the Middle Ages onwards, these halls gradually became filled with debris and collapsed building materials from the upper floor, where the city of Split had been steadily developing and growing since the early medieval period.
The western part of the Substructures opened to the public in 1959, while the eastern halls welcomed their first visitors in 1996, following extensive restoration and conservation work. Diocletian’s Palace was designated a UNESCO World Heritage Site in 1979.